Unstable angina (UA) and non-ST-segment elevation myocardial infarction (NSTEMI) accounted for 1,295,000 hospital admissions in the US in 2001, almost 60% of those patients were 65 years of age or older, and 41% were women. The National Center for Health Statistics recently reported 5,637,000 US emergency department (ED) chest-pain syndrome visits, accounting for approximately 5% of total visits. Accurate diagnosis and risk stratification of the UA/NSTEMI patient is essential to identify patients at risk and to initiate appropriate treatment.